Resilient cushion method of manufacture

ABSTRACT

A method for making a resilient cushion includes providing a particulate polymer, discrete pieces of foam and a plasticizer. The polymer, foam pieces and plasticizer are mixed and disposed in a mold. The mold is heated to cause melting of the polymer without melting of the foam. After coating of the melted polymer, a heterogeneous resilient cushion is formed with gelated polymer surrounding the discrete foam pieces.

The present invention generally relates to resilient cushions and amethod of manufacturing same. More particularly, the present inventionprovides for the manufacture of articles having controlled resilientproperties through the combination of various gels and foams.

The properties of gel/foam combinations are important in a variety ofmanufactured items. For example, resilient cushion materials findapplication in numerous toys, bicycle seats, therapeutic hand exercisinggrips, shock absorbers, acoustical insulators, vibration dampers,wrappers, hand exercisers, crutch cushions, cervical pillows, bed wedgepillows, leg rest cushions, neck cushions, bed pads, elbow pads, elbowpads, wheelchair cushions, and many pads including floor pads,orthopedic shoe soles, brace cushions and numerous other objects ofmanufacture.

An article formed from the combination of gel and foam can have itsresilient properties tailored through the use of foam of different sizesas well as resiliency depending upon the use and function of theresulting article.

As an example, foam pore size may have a significant influence on acomposite resiliency. A discussion of gel foam combinations may be hadfrom U.S. Pat. No. 5,633,286, which is incorporated herewith by thespecific reference thereto, for describing the advantages of a gel/foamcombination article.

SUMMARY OF INVENTION

A method for making a resilient cushion, which may take the form of anyof the hereinabove recited articles, generally comprises the steps ofproviding a polymer in particulate form and discrete pieces of foammaterial. The particulate polymer and foam pieces are tumbled to providea heterogeneous mixture.

A quantity of discrete pieces of foam material are provided in aselected size and thereafter the particulate polymer and foam pieces aretumbled to provide a heterogeneous mixture.

The heterogeneous mixture with plasticizer is introduced into a mold,which is thereafter heated, in order to cause melting of the polymerwithout melting of the foam. In this manner, the gelation of the meltedpolymer surrounds and encapsulates the foam particles and theheterogeneous mixture is not heated sufficiently to melt or degrade thefoam pieces therein.

The melted polymer is allowed to gelate around the foam to cause aheterogeneous resilient cushion. Alternatively, the mixture may bepassed through heated rollers which act as a continuous mold in order toform a sheet-like article or cushion.

Alternatively, a method for making a resilient cushion, which may takethe form of any of the hereinabove recited articles, may generallycomprise the steps of providing a polymer in particulate form and addinga plasticizing oil thereto in a mixer or the like. Plasticizing oil isadded in a quantity less than that to agglomerate the polymerparticulate so that the resulting mixture of plasticizing oil andpolymer particulate remains in a discrete granular, flake or particleform.

A quantity of discrete pieces of foam material are provided in aselected size and thereafter the particulate polymer and foam pieces aretumbled to provide a heterogeneous mixture.

The heterogeneous mixture with plasticizer is introduced into a mold,which is thereafter heated, in order to cause melting of the polymerwithout melting of the foam. In this manner, the gelation of the meltedpolymer surrounds and encapsulates the foam particles and theheterogeneous mixture is not heated sufficiently to melt or degrade thefoam pieces therein.

The melted polymer is allowed to gelate around the foam to cause aheterogeneous resilient cushion. Alternatively, the mixture may bepassed through heated rollers which act as a continuous mold in order toform a sheet-like article or cushion.

More particularly, the step of providing particulate polymer maycomprise the providing of a triblock copolymer elastomer in particulateform and the plasticizer may be added in the form of a plasticizing oil.

Still more particularly, the step of heating the mold may includeheating the mold to a temperature of between 150° C. and about 200° C.

Preferably, the step of providing discrete pieces of foam materialincludes providing a closed cell foam.

In an alternative embodiment of the present invention, a first amount ofpolymer in particulate form is mixed with a first amount of plasticizerand disposed in a mold. A second amount of particulate polymer isprovided along with a second amount of foam pieces which are mixed ortumbled therewith, along with a plasticizer.

The second amount of copolymer along with the foam pieces andplasticizer are added to the mold without substantial commingling withthe first amount of particulate polymer. Thereafter, the mold is heatedto cause melting of both amounts of the polymer without melting thefoam. The copolymer is allowed to cool and gelate with the first amountof melted polymer gelling into a homogeneous gel in the second amount ofmelted polymer gelling around the foam pieces to form a heterogeneousresilient cushion.

In addition, the present invention also encompasses a resilient cushionwhich is made in accordance with the hereinabove recited steps.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will be betterunderstood by the following description when considered in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a block diagram in accordance with the method of the presentinvention;

FIG. 2 is a representation of a resilient cushion made in accordancewith the present invention which includes a heterogeneous cushionincluding discrete pieces of foam surrounded by a gelated polymer;

FIG. 3 is an alternative embodiment of the present invention in which aresilient cushion is formed, similar to that shown in FIG. 1, but with agelatinous base on one side thereof;

FIG. 4 is again an alternative embodiment of the present invention,similar to that shown in FIG. 3, but with a gelatinous top layer so thatthe foam/gel combination lies between distinct layers of gelatepolymers.

DETAILED DESCRIPTION

Useful polymers in particulate form suitable for the present inventioninclude triblock copolymers which are suitable in the forming of gelcomponents. Such polymers can have a wide range of resilient propertieswhen used with varying amounts of plasticizer, for example, plasticizeroil, as is well known in the art. Such triblock copolymers include:

SEBS gels; examples include (a) Kraton G 1651.G 1654X gels; (b) Kraton G4600 gels; (c) Kraton G 4609 gels; (d) Tuftec H 1051 gels; (e) Tuftec H1041 gels; (f) Tuftec H 1052 gels.

Gels made from blends (polyblends) of (a)-(f) with other polymers andcopolymers include: SEBS-SBS gels; SEBS-SIS gels; SEBS-(SEP) gels;SEBS-(SB)n gels; SEBS-(SEB)n gels; SEBS-(SI)n gels; SEBS-(SI) multiarmgels; SEBS-branched copolymers gels; SEBS-star shaped copolymer gels;gels made from blends of (a)-(f) with other homopolymers include:SEBS/polystyrene gels; SEBS/polybutylene gels; SEBS/polyethylene gels;SEBS/polypropoylene gels.

Other suitable thermoplastic elastomers in blends suitable for makinggels include SEP/SEBS oil gels, SEP/SEPS oil gels, SEP/SEPS/SEB oilgels, SEPS/SEBS/SEP oil gels, SEB/SEBS, EB-EP/SEBS, SEBS/EB, SEBS/EP,SEPS/SEB, etc.

The following commercial elastomers can be formed with oil and incombination with other polymers into suitable gels for use in making thegel components of the composites of the invention: Shell Kratons D1101,D1102, D1107, D1111, D1112, D1113X, D1116, D1117, D1118X, D1122X, D1125XD1133X, D1135X, D1184, D1188X, D1300X, D1320X, D4122, D4141, D4158,D4240, G1650, G1652, G1657, G1701X, G1702X, G1726X, G1750X, G1765X,FG1901X, FG1921X, D2103, D2109, D2122X, D3202, D3204, D3226, D5298,D5999X, D7340, G1654X, G2701, G2703, G2705, G1705, G2721X, G7155, G7430,G7450, G7523X, G7528X, G7680, G7705, G7702X, G7720, G7722X, G7820,G7821X, G7827, G7890X, G7940; Kuraray's SEP/SEPS/SEEPS: Nos. 1001(SEP),2002(SEPS), 2003(SEPS), 2023(SEPS), 2043(SEPS), 2063(SEPS), 2005(SEPS),2006(SEPS), 1050(SEP), 2103(SEPS), 2104(SEPS), 2105(SEPS), and4055(SEEPS) manufactured by Kuraray Co., Ltd., wherein SEP is made fromhydrogenated styrene isoprene di-block copolymer (SI).

SEPS is made from hydrogenated styrene isoprene triblock copolymer(SIS),and SEEPS is made from hydrogenated styrene isoprene/butadiene blockcopolymer or more specifically made from hydrogenated styrene blockpolymer with 2-methyl-1.3 butadiene and 1.3 butadiene.

The most preferred gels forming the composites of the invention comprisea high viscosity triblock copolymers which have the more generalconfiguration A-B-A wherein each A is a crystalline polymer end blocksegment of polystyrene; and B is an elastomeric polymer center blocksegment of poly(ethylene-butylene). The poly(ethylene-butylene) andpolystyrene portions are incompatible and form a two-phase systemconsisting of sub-micron domains of glassy polystyrene interconnected byflexible poly (ethylene-butylene) chains. These domains serve tocrosslink and reinforce the structure. This physical elastomeric networkstructure is reversible, and heating the polymer above the softeningpoint of polystyrene temporarily disrupt the structure, which can berestored by lowering the temperature. This also applies to highviscosity poly (styrene-ethylenepropylene-styrene) triblock copolymers.

Various mixtures of polymer may be used as taught in U.S. Pat. No.5,633,286 hereinabove cited and incorporated herein by reference.

Plasticizers particularly preferred for use in practicing the presentinvention are well known in the art, and they include rubber processingoils such as paraffinic and naphthenic petroleum oils, highly refinedaromatic-free paraffinic and naphthenic food and technical grade whitepetroleum mineral oils, and synthetic liquid oligomers of polybutene,polypropene, polyterpene, etc. The synthetic series process oils arehigh viscosity oligomers which are permanently fluid liquid nonolefins,isoparaffins or paraffins of moderate to high molecular weight.

Examples of representative commercially oils include Amoco® polybutenes,hydrogenated polybutenes and polybutenes with epoxide functionality atone end of the polybutene polymer. Examples of such polybutenes includeL-14(320Mn), L-50(420Mn), L100(460Mn), H-15(560Mn), H-25(610Mn),H-35(660Mn), H50(750Mn), H-100(920Mn), H-300 (1290Mn), L-14E (27-37 cst@ 100° F. Viscosity), H-300E (635-690 cst @ 210° F. Viscosity), ActipolE6 (365Mn), E16 (973Mn), E23 (1433Mn) and the like. Example of variouscommercially oils include: ARCO Prime (55, 70, 90, 200, 350, 400 and thelike), Duraprime and Tufflo oils (6006, 6016, 6016M, 6026, 6036, 6056,6206, etc), other white mineral oils include: Bayol, Bernol, American,Blandol, Drakeol, Ervol, Gloria, Kaydol, Litetek, Lyondell (Duraprime55, 70, 90, 200, 350, 400, etc), Marcol, Parol, Peneteck, Primol,Protol, Sonrex, and the like.

Turning now to FIG. 1, there is shown a block diagram of the method inaccordance with the present invention. Utilizing any of the hereinaboverecited polymer particulates and plasticizers, a mixer 12 is providedfor disbursing the plasticizing oil in the polymer particulates. It isimportant that the polymer particulate maintain its individual flake orpellet structure and accordingly, plasticizing oil should not be addedin an amount to degrade the particular characteristics of the particle.

Thereafter, a tumbler 14 provides for mixing the polymer particulatewith discrete foam pieces. Alternatively, as shown in dashed line inFIG. 1, the plasticizer oil may be introduced into the tumbler with thepolymer particulate to provide a one-step tumbling/mixing action. Thetumbling is continued until the foam pieces are entirely coated orsurrounded by polymer particulate.

It should be appreciated that the characteristics of the resultantproduct are dependent upon this heterogeneous mixture of polymer andfoam pieces and accordingly, the size of the foam particles may be fromabout 1/8 inch to about 1 inch.

The shape of foam pieces may be spherical, however, a preferred shape iscylindrical. This shape facilitates the cutting of the foam pieces froma flat piece of foam material. The resiliency of the foam material maybe from about 1/2 to about 2 lbs/sq. ft. for hand cushions to from about4 to about 6 lbs/sq. ft. for floor cushions or mats. This, of course,depends upon the size and shape of the final product, the thickness ofthe final product and the desired resilient properties.

Preferably, the foam is a closed cell plastic of common usage such aspolyamides, polyimedes, polyesters, polyisocyanurates, polyisocyanates,polyurethanes, poly(vinyalcohol), for any suitable material.

Upon the homogeneous mixture, it is then passed to a mold 16, or thelike, which is heated in order to cause melting of the polyparticulatearound a discrete foam pieces 20, see FIGS. 2-4. Heating is preferablyto a temperature of between about 150° C. to about 200° C.

It should also be appreciated that the mold 16, while indicated as abatch type mold, may be a continuous type mold for the production ofsheet cushions or the like.

After cooling of the mold, the product 20, see FIG. 2, is produced,which includes gelated polymer 22 surrounding discrete pieces of foam20. It should be appreciated that the product cushion 20 may be of anysize or shape and accordingly the representation in FIG. 2 is primarilyfor showing the disbursement of foam particles 20 within a gelatedpolymer 22.

Turning now to FIG. 3, an alternative embodiment 28 made in accordancewith the present invention includes a layer 30 of gelated polymer whichmay be disposed into the mold 16 prior to the addition of theheterogeneous mixture of polymer 22 and foam pieces 20. In thisconfiguration, the layer 30 provides a firm support for an overlyingcushion 32 of gelated polymer 22 and foam pieces 20.

Since the resiliency, or rigidity of the polymer may be controlledthrough the use of plasticizing oil, the layer 30 may be rigid, or maybe flexible, depending upon the end use of the product 28.

A further embodiment 36 of the present invention is shown in FIG. 4 inwhich there are two layers 38, 40 of polymer with a heterogeneous layer42 of gel 22 and discrete pieces of foam 20. In this configuration, theproduct 36 may be used as a shock absorber, or depending upon thethickness of the layers 38, 40, it may be used as a cushion havingabrasion resistant of surfaces 50, 52, because of the superior strengthprovided by the polymer layers 38, 40.

It is important to appreciate that the present invention may bedistinguished over the prior art and that it utilizes a closed cell foamand a process of which provides for melting and gelating the polymeraround the foam without melting or physical deterioration of the foampieces.

Although there has been hereinabove described a particular arrangementof making a resilient cushion in accordance with the present invention,for the purpose of illustrating the manner in which the invention may beused to advantage, it should be appreciated that the invention is notlimited thereto.

Accordingly, any and all modifications, which may occur to those skilledin the art, should be considered to be within the scope of the presentinvention as defined in the appended claims.

What is claimed is:
 1. A method for making a resilient cushion, saidmethod comprising the steps of:providing a polymer in particulate form;providing discrete pieces of foam material; tumbling the particulatepolymer and foam pieces to provide a heterogeneous mixture; disposingthe heterogeneous mixture with plasticizer into a mold; heating the moldto cause melting of the polymer without melting of the foam; andallowing the melted polymer to gelate around the foam pieces to form aheterogeneous resilient cushion.
 2. The method according to claim 1wherein the step of providing particulate polymer comprises providing atriblock copolymer elastomer in particulate form and the method furthercomprises the step of adding a plasticizer to the heterogeneous mixture.3. The method according to claim 2 wherein the step of adding aplasticizer comprises adding a plasticizing oil.
 4. The method accordingto claim 3 wherein the step of providing discrete pieces of foammaterial includes providing a closed cell foam.
 5. A method for making aresilient cushion, said method comprising the steps of:providing apolymer in particulate form; providing discrete pieces of foam material;tumbling the particulate polymer and foam pieces to coat the foam pieceswith particulate polymer; disposing the coated pieces of foam into amold; heating the mold to cause melting of the polymer without meltingof the foam; and allowing the melted polymer to gelate around the foampieces to form a resilient cushion.
 6. The method according to claim 5,wherein the step of providing particulate polymer comprises providing atriblock copolymer elastomer in particulate form and the method furthercomprises the step of adding a plasticizer to the coated pieces of foam.7. The method according to claim 6 wherein the step of adding aplasticizer comprises adding a plasticizing oil.
 8. The method accordingto claim 7 wherein the step of providing discrete pieces of foammaterial includes providing a closed cell foam.
 9. A method for making aresilient cushion, said method comprising the steps of:providing a firstamount polymer in particulate form; mixing the first amount ofparticulate polymer with a plasticizer; providing a second amount ofpolymer in particulate form; providing discrete pieces of foam material;tumbling the second amount of particulate polymer and foam pieces toprovide a heterogeneous mixture; disposing the first amount ofparticulate polymer with plasticizer into a mold; disposing theheterogeneous mixture into the mold without substantial commingling withthe first amount of particulate polymer; heating the mold to causemelting of both amounts of polymer without melting of the foam; allowingboth amounts of melted polymer to gelate, the first amount of meltedpolymer gelating into a homogeneous gel, the second amount of meltedpolymer gelation around the foam pieces to form a heterogeneousresilient cushion having a homogeneous gel on at least a portionthereto.
 10. The method according to claim 9 wherein the steps ofproviding particulate polymer comprises providing a triblock copolymerelastomer in particulate form and method further comprises the steps ofadding a plasticizer to the heterogeneous mixture.
 11. The methodaccording to claim 10 wherein the step of adding a plasticizer comprisesadding a plasticizing oil.
 12. The method according to claim 11 whereinthe step of providing discrete pieces of foam material includesproviding a closed cell foam.